1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to controlling devices in home networks and, more particularly, to an apparatus and method for controlling devices in one or more home networks.
2. Description of the Related Art
Recently, with the development of communication and network technology, various types of home networks have been developed, and various technologies for improving user convenience when controlling and monitoring many devices which constitute a home network have been proposed. Representative examples of such technologies include Universal I Plug and Play (UPnP), Digital Living Network Alliance (DLNA) and the like.
Among them, UPnP provides a zero-configuration Plug and Play function that does not require user settings, so that a device automatically participates in a network, and dynamically acquires an Internet Protocol (IP) address, delivers functions, and identifies the presence and functions of other devices.
Meanwhile, as more homes and companies purchase additional computers, networking is recognized as a powerful means for sharing computer resources. Internet gateways are used to share Internet connections and to enable homes and companies to easily and inexpensively manage a network. Internet gateways provide Network Address Translation (NAT) as a means for connecting several hosts which share a common IP address with each other.
NAT is an Internet Engineering Task Force (IETF) standard that is used to enable several PCs and apparatuses to share a single globally routable Internet Protocol version 4 (IPv4) address in a personal network (which uses the range of a personal address such as 10.0.x.x, 192.168.x.x or 172.x.x.x). The main reason why NAT is frequently used is that there are insufficient IPv4 addresses. NAT is used for sharing an Internet connection in Microsoft Windows XP and Windows Me and other many Internet gateway devices. In particular, NAT is used for sharing a high-speed network through Digital Subscriber Lines (DSLs).
FIG. 1 is a diagram illustrating a home network using a general NAT device.
As illustrated in FIG. 1, the home network using a general NAT device includes a plurality of clients 11, 12 and 13, a NAT device 21 and a server 31.
In this case, when any one client 11 transmits a packet to the server 31, the corresponding client 11 transmits the packet, which includes a source IP address, a destination IP address, a source port, a destination port and a network protocol, to a gateway. In FIG. 1, the gateway may be understood to be the NAT device 21.
The NAT device 21 intercepts the packet delivered from the corresponding client 11 and makes a port mapping table using the destination IP address, the destination port, the external IP address of the NAT device 21, an external port, a network protocol and an internal IP address and port.
In other words, as illustrated in FIG. 2, the NAT device 21 performs conversion on the packet delivered from the corresponding client 11 through the port mapping table, and delivers it to the server 31.
In contrast, when the server 31 delivers a packet to the clients 11, 12, and 13, the NAT device 21 receives the packet from the server 31, compares the received packet with the port mapping table, and performs inverse conversion on the packet, unlike the case in which the client 11 delivers a packet to the server 31, as described with reference to FIG. 2.
However, in the case of the above-described network of FIG. 1 which uses an NAT device, the NAT device 21 must support UPnP, which was defined by the Internet Gateway Device Working Committee of UPnP Forum and, thus, UPnP Traversal, and it is difficult to apply it to a network in which a plurality of NATs are used.
Korean Unexamined Patent Publication No. 2004-39039 discloses a control message multicast method and apparatus for a UPnP-based network system, which includes SOAP/HTTPMU/UDP in UPnP device architecture version 1.0 and can transmit the same control message to a plurality of devices which exist in a UPnP network. However, the method and apparatus are related to the elimination of inconvenience in the transmission of the same control message to each device through one to one communication, and have problems in that the NAT apparatus must support UPnP and, thus, UPnP Traversal, and it is difficult to apply them to a network in which a plurality of NATs are used.